Herbs or shrubs, with milky yellow or colorless sap. Leaves mostly alternate, without stipules. Flowers regular or irregular, usually solitary and peduncled. Sepals mostly 2, sometimes united, often caducous. Petals mostly twice as many as sepals. Stamens mostly numerous, hypogynous, distinct. Pistil 1, of 2-several usually united carpels; ovary superior, usually 1-celled, with parietal placentae; style short, stigma simple or lobed. Fruit a caps., seeds usually many.
About 25 genera and 400 species, widely distributed, but most abundant in western North America. (Munz, Flora So. Calif.).